Conventionally, devices for operating a wing flap in an aircraft have a combined carrier and guide rail for a carriage movable along said rail. The flap is movably secured to the carriage by a flap mounting. The flap mounting in turn is connected to a drive mechanism through a drive lever and a drive rod. U.S. Pat. No. 4,381,093 (Rudolph), filed Oct. 7, 1980 discloses an apparatus as described above for retracting and extending trailing edge flap systems on aircraft wings. These systems function as high lift aids during starting and landing. Due to the different aerodynamic requirements to be met during starting and during landing, the rail kinematic mechanisms must be so constructed that the required flap positions can be realized. Thus, the flap positions must assure a maximum lift with a drag as small as possible during starting and a maximum lift with a drag as large as possible during landing. These requirements frequently cause a problem which resides in a relatively large structural height and structural length of said rail and kinematic mechanisms for operating the flaps. As a result, the enclosures which must envelope these mechanisms during cruising flight must thus necessarily be quite involved, whereby they tend to adversely influence the aerodynamic characteristics of the wing.